Prostate cancer is a leading cancer in men with 20,100 new cases expected in Canada in 2004 (Canadian Cancer Statistics, 2004). An even larger number of patients, following a positive PSA (prostate specific antigen) reading undergo an invasive biopsy but are not diagnosed with cancer. Unfortunately, invasive biopsy procedures require a long hospitalization with many possible side-effects. The reason for using the more invasive biopsy procedure, as opposed to the less invasive core needle biopsy is that the standard diagnostic procedure on core needle biopsy samples has not been proven to be as accurate as a more invasive biopsy and was thereby discarded as a diagnostic modality in several countries. Although the more invasive biopsies may provide a more accurate diagnosis, they are extremely traumatic for the patient. Moreover, such procedures can potentially result in long term disabilities and constitutes a significant cost to the health system.
Current diagnostic techniques for detecting prostate cancer is based on the PSA level in the serum. The final diagnosis is determined by a pathologist checking for cancer cells in the biopsy samples.
However, these present techniques are not perfect. The PSA level in the serum can be affected by factors other then cancer, including other pathologies and age. In addition, specific properties of PSA protein in serum make accurate concentration measurements very difficult. As a result, the PSA test has a large percentage of false positive as well as false negative readings. Therefore, biopsy samples are essential for more accurate diagnosis. Unfortunately, as noted above, the preferred method of biopsy, the core needle biopsy, is often inaccurate due to the very small sample size. However, genetic testing in core needle biopsy samples will allow for the accurate diagnosis without the need for more invasive methods.
There is therefore a need for a more accurate diagnostic method that does not require an invasive biopsy to detect or diagnose prostate cancer. Ideally, such a method should be usable even with very small sample sizes and may be combined with other, pathologist-based diagnosis methods.